As Comcast prepares to take over NBC Universal, one of the most difficult tasks the cable giant faces will be integrating two vastly different corporate cultures.

Melding corporate personalities has long been one of the most critical — and often overlooked — aspects to a successful deal, particularly in the egocentric media world.

If the transition to new ownership isn’t handled delicately, the financial and strategic merits of a deal are rendered moot by debilitating infighting. Just ask AOL Time Warner, Sony BMG and Paramount-DreamWorks.

Media watchers have to wonder if Comcast and NBCU will face the same ill fate. Their cultures are best embodied by their respective bosses — Brian Roberts and Jeff Zucker — who are polar opposites in their styles, according to analysts, former employees and insiders at both companies.

Roberts is a buttoned-down, bottom line-oriented exec who cares little about press attention and never lets internal battles spill into public view. He takes the Acela train when traveling between New York and Comcast’s Philadelphia headquarters.

Zucker, meanwhile, is a brash, creative type who courts the media and in true Machiavellian style lets boardroom politics play out in the press. He thinks flying commercial is a sacrifice.

“Roberts is a smart, deliberate, strategic, team focused, long-term thinker,” said one source who works with both men.

“Zucker is the opposite. He’s smart, too, but he’s also instinctive, cocky and individualistic. He wants to win today and isn’t too concerned with long-term strategic thinking.”

Comcast is a family-run firm in every way, as seen when Roberts brought his 89-year-old father, Ralph, on stage during an NBCU town hall meeting with workers.

“He was trying to signal to them that Comcast is not a company but a family with real values,” said a Comcast source in attendance. “Everyone at Comcast, from the executives to the pole climbers, knows Ralph and Brian.”

NBCU, on the other hand, has adopted parent company General Electric’s genetic code: impersonal, unfocused, and, as a result of the stress from having to meet GE’s strict financial metrics, tense.

Its culture is defined by fiefdoms whose power rises or falls based on quarterly numbers. The fact that GE boss Jeff Immelt actively avoided Zucker during a meeting with Roberts in Sun Valley, Idaho, in July is a telling indication of the mistrusting environment NBCU fosters.

“They’ve been struggling to find a strategy, so that’s made them grasp at different management approaches,” said Collins Stewart analyst Tom Eagan. For an example he cited ex-programming boss Ben Silverman who two years ago was heralded as broadcast’s savior but was pushed out earlier this year.

One of the biggest challenges is getting NBCU employees to embrace cable. Despite cable driving most of the growth at NBCU, the heart, identity, and confidence of its employees still rests with broadcast.

“It’s a fixation within the company, it’s where most of the senior executives come from, it’s where the network gets its news juice, and it’s still the power base,” said one former NBCU exec.

“Everything flows from broadcast, so no matter what Zucker says, getting killed in primetime is still hurting its self-esteem.”

This source added, “Roberts is going to have to have a really loud voice to import Comcast’s culture onto NBCU.”

For its part, Comcast seems to recognize this. “Creating a strong, disciplined corporate culture is a fundamental value at Comcast and is very important to Brian,” said a company spokeswoman.

An NBCU spokeswoman declined to comment.

Zucker seems aware as well — he’s said publicly many times that the broadcast network is 5 percent of NBCU’s bottom line and 95 percent of its perception.

The good news is that Roberts and Zucker might just be different enough to make the merger work. Sources said the two men’s styles could complement each other. And they do share some traits, among them a love for squash and making money.

On the finance side, Roberts has returned a lot of wealth to shareholders and Zucker has done an admirable job of keeping NBCU’s profits up in a troubled sector.

Roberts also knows when to open the wallet to take creative risks. According to a Comcast source, he plans to invest heavily in NBCU because he sees upsides — particularly in the film and broadcast business.

“GE wasn’t giving them any money,” this source said.

With the right resources, Zucker may well be able to restore some of NBCU’s luster. Remember, as the ex-NBCU exec said, “He’s probably one of the best news and morning producers of all time.”